pub fn odd_fibnacci_sum(threshold: u32) -> u32 {
    // 思路：按照题意生成斐波那契数列模拟即可
    let mut fib_num: (u32, u32) = (0, 1);
    let mut sum = 0;
    while fib_num.1 < threshold {
        if fib_num.1 % 2 == 1 {
            sum += fib_num.1;
        }
        fib_num = (fib_num.1, fib_num.0 + fib_num.1);
    }
    sum
}
